A beautiful widow enlists three cowboys to help her unearth money her husband stole from the U.S. Mint.

Shortly after the Civil War, Sam Whiskey, a gambler and adventurer, is seduced into helping Laura Breckenridge retrieve a quarter of a million dollars in gold bars from a sunken riverboat in Colorado's Platte River. The gold had been stolen from the Denver mint by Laura's late husband, and she is willing to pay $20,000 to have it returned before the theft is discovered and her family name is ruined. After teaming up with Jedidiah Hooker, a local blacksmith, and O. W. Bandy, an Army friend turned inventor, Sam heads for the sunken riverboat, unaware that he is being watched by Fat Henry Hobson. A diving helmet made by O. W. enables Sam to find the gold, but he loses it to Fat Henry and his henchmen. With the help of one of O. W.'s homemade machine guns, Sam and his cronies recover the loot, meet Laura, and head for Denver. Assuming the identity of a government inspector, Sam enters the mint and deliberately damages a bronze bust of George Washington. He then insists on having it repaired and takes it to a blacksmith's shop, where Jedidiah recasts the gold into the shape of the bust. Fat Henry later breaks into the shop and steals the bronze original. Sam and his men, posing as plumbers, return to the mint and recast the bust into gold bars. On a train leaving Denver the next morning, Sam splits the $20,000 with Jedidiah and O. W. but keeps Laura for himself.